This invention relates to an adjustable trailer suspension system for trailers intended for use with rail bogies.
Highway tractor-trailers have been adapted for use on railroads to promote efficient ground transportation of goods. These so-called bimodal or intermodal trailers can be used on the highway and then driven to a rail yard where they may be loaded onto the railroad. Various systems have been used to convert a trailer from highway use to railroad use. One such system utilizes rail bogies, which typically have two sets of rail wheels and a connection device. The rail bogies support the trailer on the railroad. Typically, for these systems, the trailer incorporates an adjustable suspension system that is movable between a highway mode, a rail mode, and a transition mode. In the highway mode, the suspension system is located in a normal operating position in which the suspension functions like a typical trailer suspension system. The transition mode is used when raising the trailer for loading the trailer on the rail bogie. Once the trailer has been loaded on the bogie, the suspension system is positioned to rail mode in which it is stowed away under the trailer to allow sufficient clearance between the trailer wheels and ground when the trailer is supported on the railroad by the bogie.
Various actuating systems have been used to move the suspension system between the different modes discussed above. For example, one prior art system uses the suspension system air springs to move between the highway and transition modes. However, larger than normal air springs are required to raise the trailer from highway mode to transition mode. Using larger air springs results in a more heavy and costly system that requires more maintenance. Further, the suspension characteristics needed for highway mode may be compromised.